1. Field of the Invention
The present invention relates generally to mail sorting machinery and, more specifically, to an automatic feeder module for a mail sorting system, with improved singulator and mail conveyor components.
2. Description of the Related Art
Automatic feeders for mail sorting systems are known. Generally, a stack of mail is fed to a singulator mechanism which attempts to ensure that only one piece of mail is fed at a time.
It is important for a mail sorting system that only one piece of mail be fed at a time. A system controller relies on successive pieces of mail having a predetermined spacing therebetween as they move through the induction subsystem. Various machines have been introduced to ensure single-piece feeding.
U.S. Pat. No. 4,331,328 describes a document feeder that employs a variable speed servo which drives a group of low speed rollers and a group of high speed rollers while maintaining a constant speed ratio between the two groups. A natural gap develops between first and second documents in a track of the feeder between the time the first document and the second document pass from control by the group of low rollers into control by the group of high speed rollers. A document hopper receives a stack of documents which are substantially of the same size and thickness while a flag urges the stack of documents towards the feeder rollers.
U.S. Pat. No. 4,634,111 describes a friction separation device for an automatic envelope feeder in which a stack of mail is conveyed on a conveyor belt towards a rocker pulley. Sensors detect the amount of pressure against the rocker pulley so as to control the feed rate of the conveyor 7.
U.S. Pat. No. 4,884,796 describes a singulator for a document feeder. The feeder includes a movable gate which when in a closed position sets as a fixed guide for properly aligning a stack of documents in a magazine and which when in a release position moves out of contact with the documents to relieve the friction force between the documents. The gate is moved to the released position simultaneously with the start of the pick-off means of the singulator whereby the friction force between the first and second document is substantially reduced at the instance the first document is picked off the stack.
The aforementioned automatic feeders with singulator and/or conveyor mechanisms are not particularly suitable for handling a variety of mail sizes and thicknesses. Thus, a need exists for an automatic feeder module which can effectively and reliably feed mail pieces of varying size one at a time into a mail induction subsystem of a mail sorting system.